/* jcifs msrpc client library in Java
 * Copyright (C) 2006  "Michael B. Allen" <jcifs at samba dot org>
 *                     "Eric Glass" <jcifs at samba dot org>
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package jcifs.dcerpc.ndr;

import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import jcifs.util.Encdec;

public class NdrBuffer {
    int referent;
    HashMap referents;

    static class Entry {
        int referent;
        Object obj;
    }

    public byte[] buf;
    public int start;
    public int index;
    public int length;
    public NdrBuffer deferred;

    public NdrBuffer(byte[] buf, int start) {
        this.buf = buf;
        this.start = index = start;
        length = 0;
        deferred = this;
    }

    public NdrBuffer derive(int idx) {
        NdrBuffer nb = new NdrBuffer(buf, start);
        nb.index = idx;
        nb.deferred = deferred;
        return nb;
    }


    
    public void reset() {
        this.index = start;
        length = 0;
        deferred = this;
    }
    public int getIndex() {
        return index;
    }
    public void setIndex(int index) {
        this.index = index;
    }
    public int getCapacity() {
        return buf.length - start;
    }
    public int getTailSpace() {
        return buf.length - index;
    }
    public byte[] getBuffer() {
        return buf;
    }
    public int align(int boundary, byte value) {
        int n = align(boundary);
        int i = n;
        while (i > 0) {
            buf[index - i] = value;
            i--;
        }
        return n;
    }
    public void writeOctetArray(byte[] b, int i, int l) {
        System.arraycopy(b, i, buf, index, l);
        advance(l);
    }
    public void readOctetArray(byte[] b, int i, int l) {
        System.arraycopy(buf, index, b, i, l);
        advance(l);
    }


    public int getLength() {
        return deferred.length;
    }
    public void setLength(int length) {
        deferred.length = length;
    }
    public void advance(int n) {
        index += n;
        if ((index - start) > deferred.length) {
            deferred.length = index - start;
        }
    }
    public int align(int boundary) {
        int m = boundary - 1;
        int i = index - start;
        int n = ((i + m) & ~m) - i;
        advance(n);
        return n;
    }
    public void enc_ndr_small(int s) {
        buf[index] = (byte)(s & 0xFF);
        advance(1);
    }
    public int dec_ndr_small() {
        int val = buf[index] & 0xFF;
        advance(1);
        return val;
    }
    public void enc_ndr_short(int s) {
        align(2);
        Encdec.enc_uint16le((short)s, buf, index);
        advance(2);
    }
    public int dec_ndr_short() {
        align(2);
        int val = Encdec.dec_uint16le(buf, index);
        advance(2);
        return val;
    }
    public void enc_ndr_long(int l) {
        align(4);
        Encdec.enc_uint32le(l, buf, index);
        advance(4);
    }
    public int dec_ndr_long() {
        align(4);
        int val = Encdec.dec_uint32le(buf, index);
        advance(4);
        return val;
    }
    public void enc_ndr_hyper(long h) {
        align(8);
        Encdec.enc_uint64le(h, buf, index);
        advance(8);
    }
    public long dec_ndr_hyper() {
        align(8);
        long val = Encdec.dec_uint64le(buf, index);
        advance(8);
        return val;
    }
    /* float */
    /* double */
    public void enc_ndr_string(String s) {
        align(4);
        int i = index;
        int len = s.length();
        Encdec.enc_uint32le(len + 1, buf, i); i += 4;
        Encdec.enc_uint32le(0, buf, i); i += 4;
        Encdec.enc_uint32le(len + 1, buf, i); i += 4;
        try {
            System.arraycopy(s.getBytes("UTF-16LE"), 0, buf, i, len * 2);
        } catch( UnsupportedEncodingException uee ) {
        }
        i += len * 2;
        buf[i++] = (byte)'\0';
        buf[i++] = (byte)'\0';
        advance(i - index);
    }
    public String dec_ndr_string() throws NdrException {
        align(4);
        int i = index;
        String val = null;
        int len = Encdec.dec_uint32le(buf, i);
        i += 12;
        if (len != 0) {
            len--;
            int size = len * 2;
            try {
                if (size < 0 || size > 0xFFFF) throw new NdrException( NdrException.INVALID_CONFORMANCE );
                val = new String(buf, i, size, "UTF-16LE");
                i += size + 2;
            } catch( UnsupportedEncodingException uee ) {
            }
        }
        advance(i - index);
        return val;
    }
    private int getDceReferent(Object obj) {
        Entry e;

        if (referents == null) {
            referents = new HashMap();
            referent = 1;
        }

        if ((e = (Entry)referents.get(obj)) == null) {
            e = new Entry();
            e.referent = referent++;
            e.obj = obj;
            referents.put(obj, e);
        }

        return e.referent;
    }
    public void enc_ndr_referent(Object obj, int type) {
        if (obj == null) {
            enc_ndr_long(0);
            return;
        }
        switch (type) {
            case 1: /* unique */
            case 3: /* ref */
                enc_ndr_long(System.identityHashCode(obj));
                return;
            case 2: /* ptr */
                enc_ndr_long(getDceReferent(obj));
                return;
        }
    }

    public String toString() {
        return "start=" + start + ",index=" + index + ",length=" + getLength();
    }
}